For a nonaqueous electrolyte battery, use of a zeolite-based porous material having absorptivity in order to remove residual water in the nonaqueous electrolyte solution is known. The main purpose of this is to suppress any side reactions other than the battery reaction by removing the moisture in the nonaqueous electrolyte battery, to improve the utilization efficiency, and to reduce the acid generated by hydrolysis of solutes in the nonaqueous electrolyte with residual water.
On the other hand, the zeolite-based porous material can adsorb various molecules such as those of a halogen gas, hydrogen sulfide gas, carbon dioxide, hydrocarbons, alcohols, and aromatic compounds besides water, though the kinds of the molecules to be absorbed by the zeolite-based porous material are depend on an effective diameter of molecules. Regarding the ability to absorb the various molecules, it is known to use the zeolite-based porous material to collect the gas generated by the side reaction other than the battery reaction.
When charging of the nonaqueous electrolyte battery is continued even after exceeding the rated capacity (so-called over-charge), heat is generated by electrochemical decomposition and heat degradation of the electrolyte solution, heat is generated by the chemical reaction of the electrode and the electrolyte solution, and heat is generated by heat degradation of an electrode active material itself. Accordingly, the battery may result in thermal runaway. In order to solve the problem, for a sealed type battery using a metal can for a case member, it is known to use a “rupture member” which releases the gas in the case member when the pressure in the battery is increased by the gas generated as a side reaction during over-charge and reaches a certain pressure. When the rupture member is opened, the outside air enters into the case member and thus the battery temperature is decreased, which prevents the possibility of thermal runaway occurring. When the open pressure of the rupture member is too low, it is feared that the rupture member will open at the time of usual use. On the other hand, when the open pressure of the rupture member is too high, the battery may result in thermal runaway before the rupture member opens.